JPH10261564A - Charged particle beam aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged particle beam aligner for improving throughput. SOLUTION: This device projects a small-area pattern to a wafer 2 successively for exposure while continuously moving a wafer 2 that is placed on a wafer stage 8 and a reticle 1 that is placed on a reticle stage 5 and has a plurality of small regions where a pattern is formed. In this case, the device has a polarization position correction circuit 16 for performing a first projection control for performing projection exposure while continuously and relatively moving stages 8 and 5 in a first axis direction and a second projection control for performing projection exposure while relatively and continuously moving the stages 8 and 5 in a second axial direction. Therefore, the projection exposure of the entire pattern of the reticle 1 is performed continuously onto the wafer 2 while alternately performing the continuous move in the directions of (x) and (y).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a charged particle beam exposure apparatus used for lithography of fine patterns.

[0002]

2. Description of the Related Art Conventionally, light exposure is used in an apparatus for exposing an LSI pattern on a semiconductor substrate. In recent years, as patterns have become finer, electron beam exposure, which is excellent in resolution, has been used. It is becoming. However, in the electron beam exposure, a method of drawing by a raster scan method or a variable shaping method of minute spots has been the mainstream so far, and thus throughput is lower than light exposure which can expose a pattern of one chip or a plurality of chips at once. Was inferior.

In order to improve the disadvantage of the throughput in the electron beam exposure, a method of projecting and exposing a reticle pattern onto a wafer has been proposed as in the case of the light exposure. However, when exposing a wide range, it is necessary to correct distortion in order to obtain sufficient exposure accuracy. However, it is difficult to correct this distortion with electron beam exposure, so that one or more chips are required as in light exposure. Could not be exposed all at once. Therefore, 1 on the reticle
A method has been proposed in which a chip pattern is divided into a plurality of small areas, and a pattern of the entire chip is exposed by sequentially performing projection exposure for each small area while continuously moving the reticle and the wafer.

FIG. 5 is a view for explaining the above-described exposure method, and is a perspective view of the reticle 1 and the wafer 2. Normal,
Since the pattern area 100 for one chip of the reticle 1 is larger than the deflectable width of the electron beam EB, it is divided into a plurality of areas. In FIG. 5, two regions 100a, 100a in which the width in the y direction is smaller than the width of the electron beam EB that can be deflected in the y direction.
0b. Further, each region 100a, 100b
Are divided into small regions 111 that can be collectively irradiated with an electron beam EB having a rectangular cross-sectional shape. The pattern in the pattern area 100 is projected onto a plurality of chip areas 200 on the wafer 2. Each chip area 200 is the area 100 of the reticle 1
area 200a on which the patterns 100a and 100b are projected and exposed
And 200b, and further, each region 200a, 2
00b is composed of a plurality of small areas 211 corresponding to each small area 111 of the reticle 1.

Next, the exposure operation will be described. First, area 1
In the case of projecting and exposing the pattern 00a to the region 200a of the chip 2, the reticle 1 is moved in the + x direction (the region 100a,
100b), the electron beam EB is deflected in the y direction while the wafer 2 is continuously moved in the −x direction at a constant speed, and each small area 1 is deflected in the path indicated by the broken line R1.
The pattern of each small area 111 is projected and exposed on the corresponding small area 211 of the area 200a by sequentially irradiating the small area 11. When the exposure from the left end to the right end of the region 100a is completed in this manner, the reticle 1 and the wafer 2
Is stopped, the reticle 1 is step-moved in the + y direction and the wafer 2 is step-moved in the -y direction by a predetermined amount. Next, while continuously moving the reticle 1 in the -x direction and the wafer 2 in the + x direction at a constant speed, the pattern of the small region 111 is changed from the right end to the left end of the region 100b in the same manner as in the case of the region 100a. Projection exposure is performed on 211 in order. R2 indicates the path of the optical axis AX on the reticle 1.

[0006]

As described above, the width of the region 100 in the y direction is larger than the deflectable width of the electron beam EB.
The pattern is exposed while the reticle 1 and the wafer 2 are continuously moved in one direction (x direction) for each of the regions 100a and 100b. However, between the continuous movement and the next continuous movement, y of reticle 1 and wafer 2
There is a step movement in the direction, but during this time, pattern exposure is not performed, which is a dead time and causes a decrease in throughput.

An object of the present invention is to provide a charged particle beam exposure apparatus capable of improving the throughput.

[0008]

An embodiment of the present invention will be described with reference to FIGS. (1) According to the first aspect of the present invention, the sensitive substrate 2 placed on the substrate stage 8 and the reticle stage 5
Each stage 8 is applied to a charged particle beam exposure apparatus that sequentially projects and exposes the pattern of the small area 111 to the sensitive substrate 2 while relatively continuously moving the reticle 1 having the plurality of small areas 111 on which the pattern is formed. , 5 in a first axial direction (x-direction in FIG. 3), a first projection control for projecting and exposing a pattern, and each of the stages 8, 5
The above-described object is achieved by providing a projection control circuit 16 for performing a second projection control for projecting and exposing a pattern while relatively continuously moving the pattern in a second axial direction (y direction in FIG. 3). (2) According to a second aspect of the present invention, in the charged particle beam exposure apparatus according to the first aspect, the projection control circuit 16 performs a process from the detection of the position of the reticle stage 5 to the deflection of the charged particle beam EB applied to the reticle 1. Charged particle beam EB due to time delay
And the irradiation position shift of the charged particle beam EB caused by the time delay from the detection of the position of the substrate stage 8 to the deflection of the charged particle beam EB applied to the sensitive substrate 2 is corrected. , 8 during the acceleration / deceleration movement.

In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easy to understand. However, the present invention is not limited to the embodiment.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a view showing an embodiment of a charged particle beam exposure apparatus according to the present invention, and is a block diagram showing a schematic configuration of an electron beam projection exposure apparatus. Reference numeral 3 denotes an electron optical column of the exposure apparatus. An electron beam EB emitted from an electron gun (not shown) is applied to a reticle 1 mounted on a reticle stage 5 by a reticle illumination optical system 4. Further, the electron beam EB that has passed through the reticle 1 is projected onto the wafer 2 mounted on the wafer stage 8 by the wafer projection optical system 7, and a pattern image is formed on the wafer 2. Reference numerals 10 and 11 denote laser interferometers for detecting xy positions of the reticle stage 5 and the wafer stage 8 (each stage surface is an xy surface).

Reference numeral 12 denotes a host computer for controlling the entire exposure apparatus, to which a pattern memory 13, a reticle stage control system 14, and a wafer stage control system 15 are connected. Exposure information (reticle 1) is stored in the pattern memory 13.
The reticle illumination system optical system 4 and wafer projection optical system 7 are controlled by a deflection position correction circuit 16 and an analog deflection system 17 connected to a pattern memory 13 in advance. . Reference numeral 18 denotes a stage position / speed calculation circuit for calculating the position and speed of each of the stages 5 and 8 based on detection signals from the laser interferometers 10 and 11, and the calculation results are based on a reticle stage control system 14 and a wafer stage control system 15.
And sent to the deflection position correction circuit 16.

FIG. 2 is a block diagram showing details of the deflection position correction circuit 16, wherein 301 is pattern data from the pattern memory 13, 401 to 406 are calculation data of the stage position / speed calculation circuit 18, and 401 is a reticle. Stage position signal, 402 is a wafer stage position signal, 4
Numerals 03 and 404 denote x- and y-direction velocity signals of the reticle stage 5, and 405 and 406 denote x- and y-direction velocity signals of the wafer stage 8.

Numerals 31 to 34 denote circuits for converting the pattern data 301 into coordinates on the stages 5 and 8, respectively.
Reference numeral 2 denotes a reticle stage x coordinate conversion circuit and a reticle stage y coordinate conversion circuit for calculating the x coordinate and the y coordinate of the pattern on the reticle stage.
Reference numeral 4 denotes a wafer stage x-coordinate conversion circuit and a wafer stage y-coordinate conversion circuit for calculating the x coordinate and the y coordinate of the pattern image on the wafer stage. 35-
Numeral 38 denotes a position to be irradiated with the electron beam EB and a stage by calculating a difference between the calculated x, y coordinates of each of the stages 5 and 8 and the measured values of the x and y coordinates obtained from the stage position / speed calculation circuit 18. Position error circuits for obtaining position errors of positions 5 and 8; 35 and 36 are reticle stages x
Position error circuit and reticle stage y position error circuit,
37 and 38 are a wafer stage x position error circuit and a wafer stage y position error circuit.

By the way, in the exposure apparatus shown in FIG.
In order to perform exposure while moving the stages 5 and 8 similarly to the exposure apparatus shown in FIG.
In the case where the analog deflection system 17 is controlled by using the calculation result of No. 8, a "time delay" occurs from when the electron beam EB is settled by the analog deflection system 17 after being calculated by the position error circuits 35 to 38. . Then, during this “time delay”, the stages 5 and 8 move, so that the irradiation position of the electron beam 6 shifts. In the present invention, the speed feedforward control circuits 39 to 42 are provided in order to prevent the occurrence of this shift. The speed feedforward control circuits 39 to 42 calculate the product of the actual speeds of the stages 5 and 8 obtained by the stage position / speed calculation circuit 18 and, for example, an experimentally determined “delay time”, and calculate the position error. It is added to the outputs of the detection circuits 35 to 38. In addition, 3
Reference numerals 9 and 40 denote x-speed and y-speed feedforward control circuits of the reticle stage 5, 41 and 42 denote x-speed and y-speed feedforward control circuits of the wafer stage 8, and the calculation results of each control circuit are sent to the analog deflection system 17. Is entered.

FIG. 3 shows a region 100 provided on the reticle 1.
FIG. As shown in FIG.
Are regions 51, 53, 55, and 57 in which the x direction is the longitudinal direction.
And regions 52, 54 and 56 whose longitudinal direction is the y direction. The widths of the regions 51, 53, 55, and 57 in the y direction and the widths of the regions 52, 54, and 56 in the x direction are respectively set to be equal to or less than the deflectable width of the electron beam EB.

Next, the exposure procedure will be described with reference to FIG.
First, the host computer 12 moves the reticle stage 5 and the wafer stage 8 to the exposure start position SP. For example, when the optical axis of the exposure apparatus is the exposure start position S
The reticle stage 5 is moved so as to come to P, and then stopped. Here, the setting position of the exposure start position SP is set such that the distance from the boundary of the area 100 (the distance in the x direction and the y direction) is within の of the deflectable width. Note that the wafer stage 8 is determined by the reduction ratio between the wafer and the reticle, but the description of the wafer stage 8 is omitted here.

When the movement of each of the stages 5 and 8 to the exposure start position is completed, the movement of the stages 5 and 8 is stopped once, and the host computer 12 sends an exposure start command to the pattern memory 13 and a reticle stage control system 14. Then, a movement command is issued to wafer stage control system 15. here,
The moving direction of the reticle stage 5 is the + x direction in FIG. 3, and a target position (EP shown in FIG. 3), a moving speed, an acceleration, and the like are given to each of the stage control systems 14 and 15 as parameters. The target position EP is set such that the distance from the boundary of the area 100 is within 偏向 of the deflectable width similarly to the start position SP.

When the exposure operation is started, the exposure data is sequentially read from the pattern memory 13 and input to the deflection position correction circuit 16, and the optical systems 4 and 7 are controlled by the analog deflection system 17. When recognizing that the exposure start position SP has been reached, the host computer 12 outputs the pattern data of the first exposure small area 111a (see FIG. 3B). These pattern data are stored in the reticle stage x, y
The coordinates are inputted to the coordinate conversion circuits 31 and 32 and the wafer stage x and y coordinate conversion circuits 33 and 34 and are converted into the coordinates of the respective stages 5 and 8.

For example, the coordinate data of the pattern exposed on the small area 111a is (xd, yd), and this data (xd
d, yd) are converted into reticle stage coordinates (xr, yr) and wafer stage coordinates (xw, yw) by coordinate conversion circuits 31-34. These (xr, y
r) and (xw, yw) are compared with the actually measured positions of the stages 5 and 8 in the position error circuits 35 to 38. That is, the actually measured coordinates (xrm, xrm,
yrm) and the actual measured coordinates (xwm, ywm) of the wafer stage 8 based on the position signal 402,
As the position error,

## EQU1 ## Position error circuits 35 to 38 output .DELTA.xr = xr-xrm, .DELTA.yr = yr-yrm, .DELTA.xw = xw-xwm, and .DELTA.yw = yw-ywm.

Next, the speed feedforward control circuits 39 to 42 calculate the distance corresponding to the "time delay" as the product of the actual speed of each stage and the coefficient δ corresponding to the delay time, and calculate the position errors Δxr, Δyr, It is added to Δxw and Δyw and output. For example, the actual speed of each of the stages 5 and 8 is (Vrx, Vry), (Vwx, Vwy), and the coefficient δ is δr,
Assuming that δw, the speed feedforward control circuit 39-
42 is a reticle stage coordinate (xrd, y) expressed by the following equation.
rd) and the wafer stage coordinates (xwd, ywd).

Xrd = Δxr + Vrx · δr, yrd = Δyr + Vry · δr xwd = Δxw + Vwx · δw, ywd = Δyw + Vwy · δw The deflection of the electron beam EB in the reticle illumination optical system 4 is controlled based on xrd and yrd, and the wafer projection optics. The deflection of the electron beam EB in the system 7 is controlled based on xrd and yrd.

In this way, the electron beam EB is deflected while continuously moving the reticle 1 in the + x direction, and the electron beam EB is irradiated from the left end to the right end of the area 51 in the drawing. At this time, the wafer stage 8 is moved in the −x direction. FIG.
5, an arrow R3 indicated by a broken line indicates a moving path of the optical axis on the reticle 1, similarly to R2 in FIG. 5, and the optical axis moves from SP to E by the movement of the reticle 1 in the + x direction.
Move to P. The regions 100a and 100b in FIG.
Similarly to the above, each of the regions 51 to 57 is divided into a plurality of small regions 111 as shown in FIG. 3B, and the irradiation path of the electron beam EB is, for example, a path indicated by a broken arrow R4. Since the optical axis position is SP at the start of the exposure, the electron beam EB is deflected in the x direction simultaneously with the start of the exposure, and the exposure is sequentially performed from the left end of the area 51.

When the exposure of the region 51 is completed as described above, the exposure of the region 52 is performed. The deceleration of the stages 5 and 8 is started before the optical axis reaches the target position EP, and the speed is controlled to become zero when the optical axis reaches the target position EP. The movement of each of the stages 5 and 8 in the + x direction and the −x direction is stopped, and the reticle stage 5 is continuously moved in the + y direction and the wafer stage 8 is continuously moved in the −y direction (acceleration → constant speed → deceleration). Expose the pattern. The path of the optical axis at this time is from EP to P1. Similarly, x
Exposure is performed in the order of the regions 53, 54, 55, 56, and 57 while alternately repeating the continuous movement in the direction and the continuous movement in the y direction. The path of the optical axis at this time is P
1 to P5.

In the above-described embodiment, the exposure operation is performed while the reticle 1 and the wafer 2 are continuously moved in the x direction, and the exposure is performed while the reticle 1 and the wafer 2 are continuously moved in the y direction. Is working. As a result, when exposing the pattern of the entire area of one chip, the pattern exposure can be performed with almost no interruption of the exposure operation, and the throughput can be improved as compared with the conventional case. Further, since the exposure position of the pattern is corrected based on the actually measured speeds of the reticle stage 5 and the wafer stage 8, accurate exposure can be performed even when the stages 5 and 8 are accelerated and decelerated. Can be kept smaller than the width dimension,
Further, the throughput can be improved.

FIG. 4 is a diagram showing another exposure procedure. The region 100 of the reticle 1 is divided into seven regions 61 to 67, and the stage 5 is arranged so that the optical axis takes a path of spiral movement from the periphery of the region 100 to the center on the reticle as shown by a dashed arrow R5. , 8 are controlled. Also in this case, the electron beam EB is deflected as in the case of FIG.

Also in this embodiment, since the projection exposure of the pattern is performed when the stage 5 or 8 is moved in any of the x and y directions, the throughput is improved. Also,
The pattern is also exposed during acceleration / deceleration, but the projection position of the pattern is corrected in accordance with the actually measured speed, so that the throughput can be improved while maintaining the position accuracy of the image.

In the correspondence between the above embodiment and the elements of the claims, the wafer 2 is a sensitive substrate, the wafer stage 8 is a substrate stage, the x direction is a first axial direction,
The y direction corresponds to the second axis direction, and the deflection position correction circuit 16 corresponds to the projection control circuit.

[0027]

As described above, according to the present invention,
The reticle stage and the substrate stage are first and second
The projection exposure of the pattern is performed when moving in any direction of the axial direction of the reticle, so that when exposing the pattern of the entire area of the reticle, the pattern exposure can be performed with almost no interruption of the exposure operation. Throughput can be improved. According to the second aspect of the present invention, the pattern projection position is corrected based on the actually measured speed, so that the pattern can be exposed even when each stage is accelerated or decelerated, and the position accuracy of the image is maintained. Throughput can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a charged particle beam exposure apparatus according to the present invention, and is a block diagram showing a schematic configuration of an electron beam projection exposure apparatus.

FIG. 2 is a block diagram showing details of a deflection position correction circuit 16 in FIG. 1;

3A and 3B are views for explaining an exposure procedure, wherein FIG.
The path of the optical axis at the time of the exposure operation at 00 is shown, and (b) shows the irradiation path of the charged beam EB.

FIG. 4 is a diagram showing another example of the exposure procedure.

FIG. 5 is a view for explaining an exposure method using a conventional exposure apparatus, and is a perspective view of a reticle and a wafer.

[Explanation of symbols]

 Reference Signs List 1 reticle 2 wafer 3 electron optical column 4 reticle illumination optical system 5 reticle stage 7 wafer projection optical system 8 wafer stage 10, 11 laser interferometer 12 host computer 13 pattern memory 14 reticle stage control system 15 wafer stage control system 16 deflection position Correction circuit 17 Analog deflection system 18 Stage position / velocity calculation circuit 31 Reticle stage x coordinate conversion circuit 32 Reticle stage y coordinate conversion circuit 33 Wafer stage x coordinate conversion circuit 34 Wafer stage y coordinate conversion circuit 35 Reticle stage x position error circuit 36 Reticle Stage y position error circuit 37 Wafer stage x position error circuit 38 Wafer stage y position error circuit 39,41 x speed feed forward control circuit 40,42 y speed feed forward control circuit

Claims (2)

[Claims] 1. The method according to claim 1, wherein the sensitive substrate mounted on the substrate stage and the reticle mounted on the reticle stage and having a plurality of small regions on which the pattern is formed are relatively continuously moved. In a charged particle beam exposure apparatus that sequentially projects and exposes a pattern of an area onto the sensitive substrate, a first projection control for projecting and exposing the pattern while relatively continuously moving each of the stages in a first axial direction;
A charged particle beam exposure apparatus comprising: a projection control circuit for performing a second projection control for projecting and exposing the pattern while relatively continuously moving each of the stages in a second axial direction. 2. The charged particle beam exposure apparatus according to claim 1, wherein the projection control circuit is configured to charge the device due to a time delay from a position detection of the reticle stage to a deflection of the charged particle beam irradiated on the reticle. Correcting the irradiation position deviation of the particle beam and the irradiation position deviation of the charged particle beam caused by the time delay from the position detection of the substrate stage to the deflection of the charged particle beam irradiated to the sensitive substrate, A charged particle beam exposure apparatus characterized in that the exposure operation is performed even during the acceleration / deceleration movement of the apparatus.